Over-pruning is associated with which condition due to fewer synapses?

• A. Autism
• B. Schizophrenia
• C. Bipolar disorder
• D. Obsessive-compulsive disorder

Answer: (B)

Over-pruning during development eliminates more synapses than normal, leaving neural networks with fewer connections. This pattern has been linked to schizophrenia, especially during adolescence when pruning normally refines circuits; reduced synaptic density in areas like the prefrontal cortex and temporal regions fits with the emergence of cognitive and perceptual symptoms. Some genetic and cellular evidence points to mechanisms such as complement-mediated microglial pruning contributing to the excessive synapse loss. By contrast, autism is often associated with excess synapses from reduced pruning early in development, and obsessive-compulsive or bipolar disorders do not show the same widespread synaptic loss due to over-pruning.